This PR clarifies which features are supported on P100 via its tests,
though Pascal is not officially and fully supported by Triton.
## What this PR does
- Skip unsupported tests on P100.
- Atomic RMW
- `tl.dot()` (perhaps not all patterns, but basically most `tl.dot()`
tests do not work on P100).
- Add an explicit error if shared memory size >= 64K on P100.
- Otherwise it causes `Invalid CUDA argument` error at
`cuLaunchKernel()`, but this error is not very straightforward to
understand. Instead of this generic CUDA argument error, this PR makes
Triton show an error during codegen when `sm < 70`. This check happens
in C/C++ so won't add an overhead in Triton's Python runtime.
- 3 tests (see below) are currently failing, but these are not marked as
skipped because any codegen update in the future can change the kernel
size of the other tests.
- This change won't affect Triton-MLIR. Hopefully Triton-MLIR's generic
`tl.dot()` implementation would support P100.
Importantly, Triton passed all the other tests on P100. Though this
support is not official, it is great for, for example, PyTorch's
TorchDynamo/Inductor, which can use Triton (without `tl.dot()`) for its
backend (https://github.com/pytorch/torchdynamo/issues/1591).
### Results on P100 (Google Cloud)
```sh
$ pytest test/unit
...
================================================================================== short test summary info ==================================================================================
FAILED test/unit/language/test_core.py::test_reduce2d[argmin-float32-shape99-1] - RuntimeError: Device does not support shared memory of 65536bytes
FAILED test/unit/language/test_core.py::test_reduce2d[argmax-float32-shape113-1] - RuntimeError: Device does not support shared memory of 65536bytes
FAILED test/unit/language/test_core.py::test_permute[float32-shape5-perm5] - RuntimeError: Device does not support shared memory of 67584bytes
================================================================== 3 failed, 3824 passed, 952 skipped in 470.90s (0:07:50) ==================================================================
```
<details><summary> <b>Environment Details (collapsed)</b></summary>
<p>
### VM details (Google Cloud)
https://cloud.google.com/
```
# You need a paid account (free trial does not cover GPUs)
Google Cloud -> New Project -> Compute-Engine -> VM Instance
Machine:
GPU: NVIDIA Tesla P100 x 1
CPU: 2 vCPUs, 7.5GB memory
Boot disk:
OS: Ubuntu 18.04 LTS
Disk: 40GB (cannot build Triton on the default 10GB disk)
- When I tried, about $1.2 per hour.
- US instances were full when I tried. I used Asia or Australia.
- Needed a paid account (GPU is not covered by free trial)
- Needed quota request for any GPU instance (by default, no GPU instance is allowed). Needed to wait an hour for approval
```
### Reproducer
```sh
## 1. Install CUDA and a driver
# Update the apt key (https://developer.nvidia.com/blog/updating-the-cuda-linux-gpg-repository-key/)
sudo apt-key del 7fa2af80
wget https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/cuda-keyring_1.0-1_all.deb
# Download CUDA as instructed
wget https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/cuda-ubuntu1804.pin
sudo mv cuda-ubuntu1804.pin /etc/apt/preferences.d/cuda-repository-pin-600
sudo apt-key adv --fetch-keys https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/7fa2af80.pub
sudo add-apt-repository "deb https://developer.download.nvidia.com/compute/cuda/repos/ubuntu1804/x86_64/ /"
sudo apt-get update
sudo apt-get -y install cuda
# Are you using P100?
nvidia-smi | grep "Tesla P100"
## 2. Setup the build environment
sudo apt update
sudo apt install -y build-essential wget git libz-dev
wget https://repo.anaconda.com/archive/Anaconda3-2022.05-Linux-x86_64.sh
bash Anaconda3-2022.05-Linux-x86_64.sh -b -p $(pwd)/anaconda3
eval "$($(pwd)/anaconda3/bin/conda shell.bash hook)"
conda create -y --name triton_base
conda activate triton_base
conda install -y cmake setuptools
## 3. Build Triton
git clone https://github.com/openai/triton.git
cd triton/python
pip3 install -e '.[tests]'
## 4. Test
pytest test/unit
```
### Environment
```sh
$ nvidia-smi
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 520.61.05 Driver Version: 520.61.05 CUDA Version: 11.8 |
|-------------------------------+----------------------+----------------------+
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
| | | MIG M. |
|===============================+======================+======================|
| 0 Tesla P100-PCIE... On | 00000000:00:04.0 Off | 0 |
| N/A 36C P0 25W / 250W | 0MiB / 16384MiB | 0% Default |
| | | N/A |
+-------------------------------+----------------------+----------------------+
```
</p></details>
This PR completely rewrites the runtime of Triton to be more lean and
clearly separate the compilation step from the just-in-time caching logic.
This should substantially reduce launch overhead.
This PR adds several optimization capabilities in the compiler backend:
- Now using inline PTX for `tl.store`, making it possible to use things like evict_last
- For A100, mma layout can be directly converted to shared memory
- For A100, an additional "transpose" argument in `dot` allows tensors to be loaded once and used both row- and col- major.
- Fixed liveness analysis; this was broken.
- Now can load/store directly mma layout without converting. Useful for when tl.dot accumulator is initialized with DRAM data inside of an inner loop.
- `tl.dot` can now take LHS inputs in registers when it comes from a previous `tl.dot` instruction. Useful for e.g. fused attention.
This is a more stable commit that produce bitwise identical code to earlier
versions. Using commits after this one may lead to slightly different numerics
Significantly improves the performance of `triton.ops.matmul` in memory-bound settings via the use of many more block configs coupled with a performance model to drive the auto-tuning process.
- Removed driver module -- accelerator runtime is handled by pytorch
- Added basic support for ROCM based on @micmelesse 's PR -- now can execute empty kernel on AMD devices without any compile-time changes
- Now only using PREFER_SHARED for kernels when the size of shared memory is greater than 49k. Otherwise there can be poor L1 performance for broadcast tensors
This PR adds a BF16 data-type, along with FP32 <-> BF16 conversion instructions in the LLVM codegen. Other kinds of ops on bfloat16 are not yet supported.
Improved codegen for the Ampere GPUs.
* Make the layout pass recognize the multistage pipelined pattern.
* Now the pipeline pass can automate the multistage pipelining transformation.
* Remove extra barriers (from the prefetch pass & WAR) on Ampere.
* Update the code generator (generator.cc) to make Triton generate n-buffered shared memory loads/stores.
Membar pass on top of master is buggy with asynchronous copy. For example, it doesn't wait for asynchronous copies to complete before recoalescing accumulator in GEMM, which leads to undefined behavior when the program doesn't enter the loop. This PR proposes
* Now using unordered instead of ordered float (fixes NaN issues)
* Bool -> int32 now converts to 1 rather than -1
* Reduce extend arguments to 32-bits if possible
* update membar pass when data is double buffered
* Add instruction prefetch_s
* prefetch tests pass (except the 1 warp case)
* Fix the 1-warp bug
* Add back prefetch files
* Disable prefetch on a100
* Always add war barrier on sm>=80
This massively simplifies implementation of `reassociate` and also fixes
a bunch of bug. The pass could still be improved, but can already be used
to generate constant pointer offsets in eg the matmul epilogue
This PR implements a major overhaul of the frontend for Triton, and replaces Triton-C by a pure Python API in which kernels are defined as @triton.jit decorated functions. The documentation and tutorials have also been updated to accommodate these changes.
See documentations for more information on the new API
